Скачать или смотреть How to Print Pi to Specific Decimal Places in Python

Learn how to create a Python program that reads integers and prints `Pi` to the specified number of decimal places with our simple guide.
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This video is based on the question https://stackoverflow.com/q/65890934/ asked by the user 'dolphinympho' ( https://stackoverflow.com/u/15047657/ ) and on the answer https://stackoverflow.com/a/65891072/ provided by the user 'Jailton Silva' ( https://stackoverflow.com/u/13118803/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Reading Integers and Printing Pi in Python

As a beginner in programming, you might encounter challenges while trying to tackle certain tasks. One common exercise is to create a program that reads integers from standard input (stdin) and uses those integers to determine how many decimal places of the mathematical constant Pi should be printed. This problem can seem tricky at first, particularly if you're not yet familiar with every technique available in Python. In this guide, we’ll explore how to implement a solution to this problem in a step-by-step manner.

Understanding the Problem

The goal of the program is straightforward:

Read integers from stdin.

For each integer read, print Pi to the corresponding number of decimal places.

To clarify further, if the input is 2, the output should be 3.14. If the input is 5, the output should be 3.14159. The challenge lies in correctly formatting the output based on user input.

Analyzing the Initial Attempt

Here is the code you provided:

[[See Video to Reveal this Text or Code Snippet]]

Issues Identified

String Formatting: The current implementation uses format() incorrectly. The value of number needs to be converted into an integer for the formatting to work properly.

Output: The output of this code might not yield the expected precision due to the error in formatting. The use of str(math.pi) simply converts Pi to a string, which eliminates the functionality needed for decimal place specification.

The Correct Solution

To solve the issue and create a functioning program, we recommend using the round() function instead of format(). Here’s how the updated code looks:

[[See Video to Reveal this Text or Code Snippet]]

Code Explanation

Imports: We start by importing the necessary modules. sys for reading input, and math for accessing the constant Pi.

Reading Input: Using for n in sys.stdin, we are looping through all the lines of input received.

Stripping Whitespace: The strip() method is used to clean the input by removing any extra spaces or newline characters.

Converting to Integer: We convert the stripped input string to an integer using int(). This establishes the number of decimal places we want to use.

Calculating Pi: We pull Pi from the math module.

Rounding and Printing: Finally, we round Pi to the specified decimal places and print the result.

Advantages of the Updated Code

Simplicity: The updated code directly addresses the problem by using round(), making it easier to understand and maintain.

Precision: With the round() function, you can accurately specify how many decimal places should be displayed, which directly aligns with the input provided by the user.

Conclusion

Creating a program to print Pi to a certain number of decimal places is a valuable exercise for beginners in Python. Through careful analysis of your initial code and applying a simple solution using the round() function, you can effectively accomplish your task. As you continue your programming journey, remember that understanding the basics and troubleshooting are key skills that will enhance your learning experience. Don't hesitate to experiment and try out different approaches as you grow your skills in coding!